This invention relates to a ratchet handle adapted for use with a screwdriver or the like. More particularly, this invention relates to an improved ratchet handle which provides for ratchet drive rotation in three directional modes.
There are a number of prior art disclosures directed to the use of ratchet mechanisms in conjunction with hand tools--particularly wrenches which employ a handle mechanism substantially perpendicular to the axis of rotation of the tool. The use of a ratchet mechanism in conjunction with screwdrivers and similar tools entails design constraints in terms of compactness of the ratchet mechanism and provision for an efficient applicator surface which facilitates the application of rotational force to the tool.
U.S. Pat. Nos. 1,436,640, 1,493,353, 541,130 and 4,086,831 generally disclose ratchet mechanisms employing a pair of pawls engageable with teeth at the periphery of a sprocket or gear wheel to actuate the ratchet drive mechanism. U.S. Pat. Nos. 2,013,765, 3,256,966 and 3,742,787 generally disclose ratchet mechanism employing a plurality of pawls engageable with teeth circumferentially positioned around the interior of a substantially cylindrical member to actuate the ratchet drive mechanism. The foregoing prior art ratchet mechanisms provide ratchet drive rotation in two or more directional modes.
In general, prior art ratchet mechanisms are deficient in terms of requiring a relatively large quantity of individual components which must be assembled in a relatively complex and precise manner. The latter deficiency is particularly manifest in ratchet mechanisms employing a plurality of pawls each of which require a separate spring or biasing means. The corresponding manufacturing costs are frequently disproportionate to the intended application of the ratchet mechanism for use in conjunction with basic and inexpensive tools such as a screwdriver.
The present invention is a new and improved ratchet handle employing a ratchet mechanism comprising a spring/pawl assembly which, in conjunction with a shifter assembly, provides for engagement of one or more pawls with teeth circumferentially positioned at the interior of a member to produce a ratchet drive. The present invention provides an efficient means of shifting the ratchet drive to one of three drive positions, which shifting can be accomplished by use of fingers of the same hand that holds the ratchet handle, the efficiency and ease of operation of the ratchet handle are not compromised by the manufacturing advantages. Moreover, the invention comprises a pawl assembly having a plurality of pawls which may be biased in an efficient manner by means of either an integral serpentine spring pawl structure or a single garter spring arrangement.